With rapid development of network technologies, people have increasing requirements for information, and also have higher requirements for throughout capabilities of a communications network. Therefore, it is an inevitable development trend to establish an all-optical communications network. The all-optical communications network uses a dense wavelength division multiplexing (DWDM) technology to expand capacities on a trunk and uses a reconfiguration optical add-drop multiplexer (ROADM) and an optical cross-connect (OXC) to switch a path on a cross-connect node. As a core component of the ROADM and the OXC, an optical switch is greatly important in switching an optical path on a cross-connect node.
A three dimensional (3D) micro-electro-mechanical system (MEMS) optical switch is a most important optical switch of large-scale optical switches. The optical switch includes an input collimator array, an input MEMS chip, an output MEMS chip, and an output collimator array. Both the input collimator array and the output collimator array include an optical fiber array and a lens array, and both the input MEMS chip and the output MEMS chip include a micromirror array. Each micromirror of the micromirror array may rotate around two perpendicular axles that are on a surface of the input MEMS chip or the output MEMS chip. An optical signal is transmitted, through an optical fiber array of the input collimator array, to a lens of a corresponding lens array, and is incident on a micromirror of a micromirror array on the input MEMS chip. The optical signal is reflected to a micromirror of a micromirror array on the output MEMS chip by rotating the micromirror on the input MEMS chip, reflected to a lens of a lens array of the output collimator array by rotating the micromirror on the output MEMS chip, and then output using an optical fiber corresponding to the lens of the output collimator array. In order to ensure that the optical signal reflected by the micromirror of the micromirror array on the input MEMS chip is not blocked by the input collimator array and is reflected to the micromirror of the micromirror array on the output MEMS chip, an included angle β exists between a surface of a lens array of the input collimator array and a surface of the micromirror array on the input MEMS chip and between a surface of the micromirror array on the output MEMS chip and a surface of the lens array of the output collimator array. Lenses of the lens array of the output collimator array are arranged at an equal spacing L in two perpendicular directions on the surface of the lens array. Micromirrors of the micromirror array on the output MEMS chip are arranged at the equal spacing L in one of two perpendicular directions on the surface of the micromirror array, and arranged at an equal spacing L/Cos β in the other direction.
The angle β is basically different for optical switches of different sizes. In this case, for the optical switches of different sizes, spacings between micromirrors of micromirror arrays on MEMS chips thereof are different. Therefore, there is a need to design different MEMS chips for optical switches of different sizes. This leads to relatively complex design and manufacturing processes of optical switches of multiple sizes.